Thickened alkali metal hypochlorite bleaching and cleaning composition

ABSTRACT

AQUEOUS ALKALI-METAL HYPOCHOLRITE SOLUTIONS INCORPORATING MIXTURES OF C8-C18 ALKALI-METAL SOAPS AND HYDROTROPES, GENERALLY AMINE OXIDES AND BETAINES, AND THEREBY HAVING INCREASED VISCOSITIES, ARE DISCLOSED. THE THICKENED SOLUTIONS POSSESS ENHANCED CLEANSING AND DISINFECTING ABILITIES. THE PERFUMING OF THESE THICKENED SOLUTIONS IS ALSO DISCLOSED.

United States Patent ce 3,684,722 Patented Aug. 15, 1972 US. Cl. 252-98 6 Claims ABSTRACT OF THE DISCLOSURE Aqueous alkali-metal hypochlorite solutions incorporating mixtures of C -C alkali-metal soaps and hydrotropes, generally amine oxides and betaines, and thereby having increased viscosities, are disclosed. The thickened solutions possess enhanced cleansing and disinfecting abilities. The perfuming of these thickened solutions is also disclosed.

This invention relates to the improvement of the physical and commercially-useful properties of aqueous alkali-metal hypochlorite solutions suitable for laundry, general domestic bleaching and disinfectant purposes.

Aqueous alkali-metal hypochlorite solutions are available commercially in the form of concentrated solutions containing about 15% available chlorine, and for general household use are diluted with water to concentrations of from 1 to 10% available chlorine. Conventionally concentrations of and available chlorine are used, and these concentrations approximately correspond to concentrations of 5 and 10% by weight of alkali-metal hypochlorite in the solutions. In addition, up to 2% by wegiht of free caustic alkali is normally also present in commercially available solutions.

Apart from their use as bleaching agents in the treatment of fabrics, such compositions are frequently employed as bleaching and disinfectant cleaners for lavatory pans, urinals, drains, wastepipes and the like.

The present invention provides a bleaching composition comprising Water, an alkali-metal hypochlorite, a hypochlorite-soluble surface active agent, preferably an amine oxide, and an alkali-metal salt of a C to C fully saturated fatty acid. Optionally, a caustic alkali may be included.

By the present invention it has been found that the aqueous solution of alkali-metal hypochlorite can be satisfactorily thickened if to it is added a hypochlorite-soluble surface active agent and an alkali-metal salt of a C to C fully saturated fatty acid, and that a hypochlorite solution thickened in this manner can be readily perfumed.

The efliciency of alkali-metal hypochlorite solutions for the latter purpose is increased by making the solutions more viscous so that they can therefore adhere longer to vertical and inclined surfaces.

A further advantage of an aqueous alkali-metal hypochlorite solution having an increased viscosity is that the solution could act as a carrier for hypochlorite-stable colourants, and the coverage of surfaces could thereby be much more readily assessed by the user than with the conventional colourless or straw-coloured solutions.

Also, it has been proposed hitherto to add a perfume to aqueous alkali-metal hypochlorite solution, the perfume being solubilised with the aid of a specific surface active agent.

Thus it is desirable that an aqueous alkali-metal hypochlorite solution be prepared that has an increased viscosity and which also can be satisfactorily perfumed.

In a particularly preferred embodiment of the invention, a bleaching composition comprises water, an alkalimetal hypochlorite, a perfume, preferably in an amount of from about 0.05 to about 0.2% by weight of the composition, a hypochlorite-soluble surface active agent, preferably an amine oxide, an alkali-metal salt of a C -C fully saturated fatty acid, the weight ratio of the hypochlorite-soluble surface active agent to the alkali-metal salt of the fatty acid being from about 90:10 to about 70:30, preferably from about :20 to about 70:30, and the weight ratio of the total surface active agent content of the composition to the amount of perfume present in the composition being not less than about :15, preferably from about 88:12 to about :5. Optionally, a caustic alkali may be included.

Extensive trials (as shown below in examples 1 and 2) with conventional thickeners failed to provide satisfactorily thickened compositions. The compositions obtained employing conventional thickeners suffered from one or more of the following deficiencies:

(1) The thickener was decomposed by the alkali metal hypochlorite;

(2) The alkali metal hypochlorite was decomposed by the thickener;

(3) No thickening was achieved, or the thickening obtained was only temporary and phase separation occurred on standing.

In applying the principle of the invention, the selection of the hypochlorite-soluble surface active agent has to be made with care. It will be apparent that this surface active agent must be resistant to attack by the alkali-metal hypochlorite on standing, so that there is no chemical interaction between the thickening ingredients and the alkalimetal hypochlorite resulting in a loss of available chlorine and a corresponding loss in bleaching and disinfectant performance, and possible drop in the increased viscosity.

Examples of hypochlorite-soluble surface active agents that have been found to be particularly well-suited to the purposes of the invention are amine oxides and long-chain substituted betaines.

The amine oxides have the structural formula:

R2 R -I I-)O Ifta wherein R is a C -C alkyl group, preferably a C 4) alkyl group, and R and R can be short-chain alkyl groups, such as methyl, ethyl, n-propyl and iso-propyl. R and R will generally be the same, but can differ if this is desired. Typical amine oxides suitable for the present invention are lauryl di-methylamine oxide, myristyl di-methylamine oxide, cetyl di-methylamine oxide, coconut di-methylamine oxide, hardened tallow di-methylamine oxide, hexadecyl di-methylamine oxide, lauryl di-ethylamine oxide, and coconut di-ethylamine oxide.

Long-chain substituted betaines suitable for the invention are compounds having the structural formula:

wherein R is a C -C alkyl group, preferably a C -C alkyl group, and R R and R are C C, alkyl groups. Specific examples of suitable betaines are octyl, decyl, dodecyl, tetradecyl, hexadecyl and octadecyl dimethyl betaines in which R, is an alkylene group with 2 or 3 carbon atoms.

The alkali-metal salt (soap) of a fatty acid will usually be the sodium salt, but potassium or lithium salts can also be used. The fatty acid can be any natural or synthetic C C fully saturated fatty acid, such as caprylic 3 acid, capric acid, lauric acid, myristic acid, palmitic acid and stearic acid, and the mixtures of fatty acids, suitably hardened, derived from such natural sources as tallow, coconut oil, groundnut oil and babassu oil can be used.

These soaps will not disperse in hypochlorite solution without the aid of a hydrotrope, and the presence of the hypochlorite-soluble surface active agent meets this requirement. A preferred soap is an alkali-metal laurate. Soaps with a shorter carbon chain have been found to be less effective thickeners, and soaps of a higher carbon chain length are less soluble in hypochlorite solution, the insolubility increasing with increasing chain length.

It has been found that, generally, satisfactory thickening can be obtained using a concentration of the hydrotropesoap mixture of from 0.5-2.5%, but in many instances satisfactory thickening is obtainable if the mixture is employed below a concentration of 0.5%. In general, thickening increases with increasing content of thickening mixture. There is often no objection to the use of amounts of thickening mixture above 2.5%, provided the available chlorine stability is maintained. The hydrotropersoap weight ratio can vary between 90:10 and :80. The preferred hydrotrope:soap weight ratio is 80:20 to 60:40. As the proportion of hydrotrope is reduced there is a tendency for the soap to come out of solution.

A suitable way of incorporating the thickening mixture is to form a pre-mix of hydrotrope and soap in warm water, and then add hypochlorite solution to the pre-mix to obtain the desired final composition.

The alkali-metal hypochlorite will usually be sodium hypochlorite, but potassium hypochlorite and lithium hypochlorite may be used if desired. The alkali-metal hypochlorite will generally comprise from 1 to 10% by weight of the bleaching composition.

Although not an essential ingredient of a bleaching composition of the invention, a caustic alkali is generally incorporated into liquid compositions of this type, and hence a bleaching composition of the invention can include a caustic alkali, preferably in an amount from 0.5 to 2% by weight, if desired. The caustic alkali will usually be sodium hydroxide, but potassium hydroxide and lithium hydroxide may also be used.

The increased viscosity of the composition due to the presence of the thickening agent improves the cleaning and disinfecting properties of the composition by increasing its tendency to adhere to treated surfaces, for example the internal surfaces of lavatory pans. The preferred viscosity for this purpose is between 10 and 100 centistokes (cs.) at C., as measured using an Ostwald viscometer.

If an aqueous hypochlorite solution is thickened according to the invention, and subsequently a perfume is added to the thickened solution, it is found that the addition of the perfume results in a significant reduction in the overall stability of the thickened solution. Thus, although it might be expected that the presence of surface active material in the thickened hypochlorite solution would act as a good solubiliser for a perfume, because of the instability problem the perfuming of a thickened hypochlorite solution is not a simple matter of the mere addition of a perfume to the solution.

Experiments have shown that the effects produced by the addition of a perfume to a thickened hypochlorite solution depend on four factors, namely the concentration of the perfume, the ratio of the hypochloritesoluble surface active agent to the alkali-metal fatty acid salt, the total surface active agent concentration, and the type of perfume involved.

The addition of a perfume to a thickened hypochlorite solution generally produces some increase in the viscosity of the solution, and always results in a decrease in the overall stability of the whole system. The solution becomes more unstable as more perfume is added. The preferred perfume concentration range is from about 0.05 to about 0.2% by Weight.

The ratio of the hypochlorite-soluble surface active agent to the alkali-metal salt of the fatty acid is important and, as in the case of the unperfumed thickened hypochlorite solutions described above, an increase in this ratio is generally accompanied by an increase in stability, but a decrease in viscosity. The effect of the addition of a perfume can, to some extent, be counteracted by careful variation of this ratio. In a perfumed thickened hypochlorite solution the ratio should be between about 90: 10 and about 70:30 preferably about :20 to about 70:30.

In an unperfumed thickened hypochlorite solution the total surface active agent concentration is not generally significant as far as stability is concerned, as a given ratio of hypochlorite-soluble surface active agent to alkali-metal fatty acid salt is stable irrespective of the total amount of surface active agent present. However, if a perfume is added to the thickened solution the ratio of the total concentration of surface active agent present to the concentration of perfume present becomes important, and we have found that this ratio should be at least about :15, preferably from 88:12 to about :5.

The nature of the perfume incorporated into a thickened hypochlorite solution also influences to some extent the effect of the perfume on the thickened solution, although this generally can be taken care of when adjustments to the basic thickened formulation are made to bring it into line with the requirements outlined above. Perfumes can either be single compounds, or blends of two or more compounds in a variety of different proportions. It will be apparent that the constituents of a perfume should be substantially stable to hypochlorite solution in order to make the perfume suitable for the present invention.

The following examples, in which all parts and percentages are by weight, illustrate the difficulties involved in developing a satisfactorily thickened aqueous hypochlorite solution, and also illustrate bleaching compositions in accordance with the invention.

EXAMPLE 1 The following polymers were obtained from various manufacturers and their ability to thicken sodium hypochlorite solution investigated.

(a) Texigel polymersex Scott Bader (b) Primal/Acrysol-ex Lennig (c) Sedomax-ex I.C.I.

(d) Separan-ex Dow (e) Cyanamer-ex Cyanamid (f) Manucol Esters-ex Alginate Industries (g) Viscofas/ polyvinyl alcoholex I.C.I./Hoechst (h) Gelgard-ex Dow (i) Polyox--ex Union Carbide (j) Texamid-ex Henkel (k) Polytericsex Glovers (l) Polymer x 150ex Union Carbide (m) Montrek 600E-ex Dow In addition Veegum T (ex Greef-a blend of silicates having high magnesium content) was also evaluated.

Method In order to prevent any excess agitation of the hypochlorite solution, which increases decomposition, and to ascertain the reduction of thickening caused by addition of 10% (available chlorine) hypochlorite solution, each polymer was dissolved as a viscous stock solution in water and then diluted with a similar volume of hypochlorite solution to give an available chlorine of about 5%.

In most cases, preparation of the stock solution consisted only of the addition of polymer, if a powder, to cold distilled water with mechanical stirring. The Viscofas/;polyvinyl alcohol stock solution was obtained by dissolving Viscofas L in a solution of polyvinyl alcohol at about 80 C .In the case of Montrek 600E and Polymer x 150, which are liquids, they were merely added to 5% (available chlorine) hypochlorite solution.

The preparation of polyacrylate thickeners was, however, more complicated. These consist either of polyacrylic acids, or their sodium or ammonium salts. Addition of an acid to sodium hypochlorite solution causes evolution of chlorine and also reduces the free alkali level, a factor necessary for stability. The preparation of each stock solution therefore, included the addition of sodium hydroxide to form the sodium salt of the polyacrylic acids in alkaline solution. This was then diluted with 10% (available chlorine) sodium hypochlorite solution. The thickened hypochlorite solution thus obtained with Texigel and "Acrysol polyacrylates was placed on storage at room temperature and 37 C. and observed for changes in viscosity and available chlorine. Samples were also prepared containing ultra-marine R.S.l. pigments, attempting to suspend them by means of the thickener.

The thickening effect of each polymer is summarised in Table I whilst available chlorines for polyacrylate-thickened samples are recorded in Table II.

Veegum T was incorporated in hypochlorite solution by preparing a stock by addition of the solid to mechanically stirred water and then diluting with (available chlorine) hypochlorite solution in the ratios of 9:1, 8:2, 7:3, 6:4 and 5:5. The resulting compositions ranged from water-like solutions to thick pastes. Each was then observed for stability of thickness, but in all cases the Veegum T began to precipitate after a few hours.

Results No further available chlorine measurements were taken as the viscosity began to decrease after 3 weeks storage at room temperature.

Conclusions EXAMPLE 2 This example illustrates the unsuitability of a number of conventional thickeners as thickeners for hypochlorite solution. The concentration of sodium hypochlorite in the solutions used in this example was 5%.

(a) Polymers and celluloses (l) Methofas PL (5) Laponite CP (2) Cellofas B (6) Devlex 130 (3) Polypeptide 37 (7) Polyvinylpyrolidine (4) Natrosal (8) Modocoll E [(a) Polyaerylates] Polymer Grade Observations Texigel 1 ET8 Viscous up to 6 weeks ultramarine supported for three weeks only, (all in viscosity caused precipitation. A3 Only small thickening efiect. Primal l figggg Viscous at first but viscosity increase neglibible after 7 dave G Caused evolution of gas. Sedomax HP No thickening efiect after 1 hour.

(b) General Grade Description Observations NP 10 Separan. gi0 Polyacrylamide No thickening etlect. Cyanamer 2 5/(5 5::: f flyac 'ylamide I D o. is it in n m f 3 gina es.. n ia v cos y crease he i e a ter Mamie)! Ester" {SA/LM hours storage. g g Viscofas Lioo/ Methyl vinyl ether- "Lumpy after three hours storage.

polyvinyl alcohol. maleic anhydride copolymer. Gelgard. lgg Nature unknown No thickening effect. Polyox WSRN3000..{WSR 301:::::}Polyg1ycol Do.

Coagulant g; :::"::':}Nature unknown Thickening unstable after 3 hours. Texamid 768.... do Rapid evolution of chlorine thickening nil 778 i after 12 hours. Polyteric fi: uA g }No thickening efiect. Polymer- X15 Cationie Do. Montrek 600E Ethoxylated poly- Do.

ethyleneimine.

1 All the above samples were in 5% (available chlorine) hypochlorite solution. Both 'lexlgel and Primal samples gave ofi a sweet smell after short periods of storage, suggesting decomposition.

TABLE IL-AVAILABLE CHLORINES OF TEXIGEL SAMPLES Figures recorded after two weeks storage Each of these was added to hypochlorite solution at 0.1% and solubility, stability and thickness were observed:

(1) Did not dissolve at all even with Ambiteric D present.

(2) Dissolved very slowly.

(3) Dissolved well but much gas was evolved.

(4) Dissolved slowly with gas evolution.

(5) Did not dissolve, even with Ambiteric D present.

( 6) Did not dissolve, even with Ambiteric D present.

(7) Dissolved Well, no gas evolved.

(8) Did not dissolve in hypochlorite.

The viscosities of (2), (3), (4) and (7 were measured but were not significantly greater than the viscosity of untreated hypochlorite solution. The concentration of thickener in (2), (3), (4) and (7) was increased to 0.5%, this had little eifect on the viscosity, so the thickener concentration was increased to 2.5%.

(b) Silicones (l) Silicone Fluid Flll/IOOOO (I.C.I.).

(2) Silicone MS.

Both were immiscible with hypochlorite solution, even with Ambiteric D present.

(c) Water glass (sodium silicate solution) Water glass was added to hypochlorite solution, but even at it did not thicken the solution appreciably.

(d) Bentonite Several methods were tried to incorporate bentonite in hypochlorite solution:

(1) Direct addition of the powder to the hypochlorite solution.

(2) Making a paste of the powder in water and adding this to the hypochlorite solution.

(3) Mixing the powder with Ambiteric D and adding this to the hypochlorite solution.

All these methods were unsuccessful, the bentonite rapidly settling out. No thickening was noticed.

(e) Liquid paraffin/hypochlorite solution emulsions Emulsions were made containing varying amounts of hypochlorite solution and liquid paraffin. Concentrations tried were:

Percent of Emulsion 1 2 3 4 5 6 7 Hypochlorite solution- 87. 5 75 62. 5 50 37. 5 12. 5 Liquid parafiin 12. 5 25 37. 5 50 62. 5 75 87. 5

In all cases 0.3% Ambiteric D Was added as an emulsifier. Samples 6 and 7 were very thick and did not settle out. All the rest settled fairly rapidly. Several thickeners were added to the emulsions 1-5 to try to thicken and stabilise them. Borax, sodium stearate and stearic acid were all tried, of which stearic acid was the best. It made mixtures 3, 4, and 5 very thick when added at 5%, but

for the hypochlorite solution/paraffin emulsions without success were gelatin, saponin, Span 20, Span 60, Teepol, DOBS 83 and Empicol 0319.

(f) Sodium stearate/hypochlorite solution emulsions Solutions containing 5, 10, 15, 20 and 25% sodium stearate in water were emulsified. After a long period of stirring, all became creamy and thick. Each of these emulsions was added to an equal weight of hypochlorite solution and the mixtures stirred thoroughly. These mixtures thus contained 2.5, 5, 7.5, 10, 12.5% sodium stearate. All separated out after 23 hours.

The following are exemplary of the hydrotrope/soap compositions of the invention. In all of these examples the solution thickened was a sodium hypochlorite solution with 10% available chlorine. Samples were prepared at three different concentrations of free alkali in each case (sodium hydroxide concentrations 0.5, 1.0 and 2.0%

Hydrotropezsoap Example Hydrotrope Soap ratio 3 Ammonyx LO (lauryl Lithium caprylate-- 80:20

di-methylamine oxide). Ammonyx LO :40 d :20 60:40 80:20 d0 80:20 Ammonyx MO Lithium eaprate 20: 80

(myristyl dimethylamine oxide). 10- Ammonyx MO do 60:40 11-. -do 80:20 12 Ammonyx CO (cetyl Sodium eaprate 80:20

dimethylamine oxide). Ammonyx 00 do 60:40 Sodium 111 80:20 do 60:40 Lithium myristate. 80:20 Sodium palmitate... 80:20 J 60:40 Lithium palmitate- 20:80 do 60: 40 80:20 S0d1umlaurate 80:20 23- ..do Lithium 1aurate 80:20

The concentration of thickening mixture employed in all cases was 0.5%.

EXAMPLES 24-31 To an aqueous hypochlorite solution having 10% available chlorine were added the ingredients as shown in Table III, and the viscosity of each example was determined using an Ostwald viscometer at ambient temperature (25 C.).

TABLE III Total surface active Ratio 01' Perfume agent surface concen- Hydr0- Soap 2 Ratio of concenactive Vistration trope 1 (perhydrotration agent to cosity (percent) (percent) cent) tropezsoap (percent) perfume (cs.)

1 An amine oxide sold under the trade name Ammonyx L0 byNovadel Ltd., as a 30% solution in water, and incorporated in the above formulations as such.

8 A perfume blend, the main constituents of which were: Bornyl acetate, 30%; Lin- Terpineol (crude), 20%.

A perfume blend, the main constituents of which were: Tcrpene hydrocarbons, 10%; Cineole, 15%; Linalol, 30%; Camphor, 10%.

5 Pure Cineole. A perfume blend, the main constituents of which were: Terpcne hydrocarbons, 5%; Cineole; 77%, p-Oresol, 15%.

would not mix with 1 and 2. The emulsions 3, 4 and 5 with 5% stearic acid added did not separate out rapidly,

The formulations of Examples 2330 were stable, and retained their viscosity and perfume satisfactorily on but were very lumpy. Other emulsifiers which were tried 75 storage.

9 EXAMPLE 32 A bleaching composition according to the invention is made by admixture of the following components:

Water to 100%.

1 A betaine sold under the trade name Ambiteric D by Glovers Chemicals Limited, and having the structural formula wherein R1 is a C12 alkyl group, R2 and R3 are methyl groups. and R4 contains 2 carbon atoms.

2 A perfume blend, the main constituents of which were:

Percent Terpene hydrocarbons Cineole Linalol 30 Camphor 10 This composition was stable, and retained its perfume and viscosity on storage. Its viscosity was 15 cs.

What is claimed is:

1. A liquid bleaching composition consisting essentially of:

(a) an alkali-metal hypochlorite selected from the group consisting of sodium hypochlorite, potassium hypochlorite and lithium containing about 1 to about 10% available chlorine;

(b) a hypochlorite-soluble surface active selected from the group consisting of C -C alkylamine oxides and (I -C alkyl-substituted betaines, together with a soap selected from the group consisting of the sodium, potassium and lithium salts of C -C saturated fatty acids, the weight ratio of the hypochloritesoluble surface active agent to the soap being from about 90:10 to about 20:80 and the hypochloritesoluble surface active agent and the soap together comprising from about 0.5 to about 2.5 percent by weight of the composition;

(c) the remainder of the composition being essentially water, said composition having a viscosity of between 10 to 100 centistokes at 25 C.

2. A liquid bleaching composition according to claim 1, in which the weight ratio of the hypochlorite-soluble surface active agent to the soap is from about :20 to about 60.40.

3. A liquid bleaching composition according to claim 1, in which:

(a) the weight ratio of the hypochlorite-soluble surface active agent to the soap is from about 10 to about 70:30; and

(b) The composition additionally comprises from about 0.05 to about 0.2 percent by weight of a perfume and the weight ratio of the hypochlorite-soluble surface active agent and the soap, taken together, to the amount of perfume present in the composition is at least about 85:15.

4. A liquid bleaching composition according to claim 3, in which the weight ratio of the hypochlorite-soluble surface active agent to the soap is from about 80:20 to about 70:30.

5. A liquid bleaching composition according to claim 3, in which the weight ratio of the hypochlorite-soluble surface active agent and the soap, taken together, to the amount of perfume present in the composition is from about 88: 12 to about :5.

6. A liquid bleaching composition according to claim 5, in which the weight ratio of the hypochlorite-soluble surface active agent to the soap is from about 80:20 to about 70: 30.

References Cited UNITED STATES PATENTS 3,113,928 12/ 1963 Davis et al 25298 3,388,069 6/1968 Lindner et a1. 25299 3,441,507 4/1969 Schiefer et a1. 25298 LEON D. ROSDOL, Primary Examiner I. GLUCK, Assistant Examiner U.S. Cl. X.R. 

